1. Field of the Invention This invention relates to a method for manufacturing a display device containing at least two mutually parallel plates which are connected tightly at their edges via a frame, and to the manufactured display device. At least one plate is coated with a pattern of separately addressable electrodes which are each brought to the outside through the frame.
2. Description of the Prior Art
German Published Non-Prosecuted Application No. DE-OS 29 31 077 (U.S. Pat. No. 4,340,838) describes a flat picture screen in a gas discharge display device in which a gas discharge furnishes electrons which are drawn through selected holes of a control matrix into a space free of plasma, wherein energies of several kV are absorbed and finally strike a fluorescent screen. The control matrix is formed by individually addressable row and column conductors which are arranged on both sides of an insulating plate and are preferably generated as follows: First, an adhesion-promoting aluminum oxide layer 20 nm thick is vapor-deposited on the plate and this is followed with a vapor deposited copper conduction layer 300 nm thick. This metallization is subsequently given a photoresist mask which leaves only the desired electrode patterns free. The bare copper regions are reinforced by electroplating, more specifically, first, with copper 3 .mu.m thick for improving the conductivity and thereafter, with 1 .mu.m nickel as corrosion and sputter protection. Thereupon, the resist is removed and the exposed titanium/copper areas are etched off.
In order to build up a gastight envelope with such an electrode plate, all cell parts to be connected together (plates and optionally required spacer frames) could be made of glass and fused to each other (see in this connection DE-OS No. 26 15 721 corresponding to U.S. Pat. No. 4,112,329 which is referred to in DE-OS No. 29 31 077, which corresponds to U.S. Pat. No. 4,340,838). Such fusing technique, however, can be considered only in exceptional cases if only for the reason that they require conductor and insulating materials which are extremely heat-resistant.
An ideal situation would be one in which the glass parts could be solidified with each other by a low-melting glass solder. Practice has shown, however, that leaks and cracks in the plates always occur in the vicinity of the glass solder seam. These defects are probably related to the fact that glass adheres poorly on nickel; that nickel itself is not particularly ductile; and the entire soldering zone is subjected to strong thermal stresses after cooling off. Nickel is not replaceable without difficulty, especially since it can be very conveniently deposited electrolytically. In any case, the wettability could be improved substantially with a specific surface oxidation. Such oxidation, however, is not always successful and is in addition very costly because the conductors must remain bare in the vicinity of the display panel where surface oxides would lead to contrast variations.